function calcStar(str) {
  if (typeof str !== 'string') {
    throw Error("所传参数必须是字符串");
  }
  switch (str) {
    case 'actived':
      return '/static/img/star_02.png'; break;
    case 'half_actived':
      return '/static/img/star_03.png'; break;
    case 'unactived':
      return '/static/img/star_01.png'; break;
    default: break;
  }
}
module.exports = {
  calcStar
}